﻿package andy.demo.mutitouch;
	import android.content.Context;  
	import android.graphics.Canvas;  
	import android.graphics.Color;  
	import android.graphics.Paint;  
	import android.view.MotionEvent;  
	import android.view.SurfaceHolder;  
	import android.view.SurfaceView;  
	   
	public class MTView extends SurfaceView implements SurfaceHolder.Callback {  
	   
	    private static final int MAX_TOUCHPOINTS = 10;   //最多可以進行10點觸摸
	    private static final String START_TEXT = "请随便触摸屏幕进行测试";  
	    private Paint textPaint = new Paint();  
	    private Paint touchPaints[] = new Paint[MAX_TOUCHPOINTS];  
	    private int colors[] = new int[MAX_TOUCHPOINTS];  
	   
	    private int width, height;  
	    private float scale = 1.0f;  
	   
	    public MTView(Context context) {  
	        super(context);  
	        SurfaceHolder holder = getHolder();  
	        holder.addCallback(this);  
	        setFocusable(true); // 确保我们的View能获得输入焦点  
	        setFocusableInTouchMode(true); // 确保能接收到触屏事件  
	        init();  
	    }  
	   
	    private void init() {  
	        // 初始化10个不同颜色的画笔  
	        textPaint.setColor(Color.WHITE);  
	        colors[0] = Color.BLUE;  
	        colors[1] = Color.RED;  
	        colors[2] = Color.GREEN;  
	        colors[3] = Color.YELLOW;  
	        colors[4] = Color.CYAN;  
	        colors[5] = Color.MAGENTA;  
	        colors[6] = Color.DKGRAY;  
	        colors[7] = Color.WHITE;  
	        colors[8] = Color.LTGRAY;  
	        colors[9] = Color.GRAY;  
	        for (int i = 0; i < MAX_TOUCHPOINTS; i++) {  
	            touchPaints[i] = new Paint();  
	            touchPaints[i].setColor(colors[i]);  
	        }  
	    }  
	   
	    /*  
	     * 处理触屏事件  
	     */  
	    @Override  
	    public boolean onTouchEvent(MotionEvent event) {  
	        // 获得屏幕触点数量  
	        int pointerCount = event.getPointerCount();  
	        if (pointerCount > MAX_TOUCHPOINTS) {  
	            pointerCount = MAX_TOUCHPOINTS;  
	        }  
	        // 锁定Canvas,开始进行相应的界面处理  
	        Canvas c = getHolder().lockCanvas();  
	        if (c != null) {  
	            c.drawColor(Color.BLACK);  
	            if (event.getAction() == MotionEvent.ACTION_UP) {  
	                // 当手离开屏幕时，清屏  
	            } else {  
	                // 先在屏幕上画一个十字，然后画一个圆  
	                for (int i = 0; i < pointerCount; i++) {  
	                    // 获取一个触点的坐标，然后开始绘制  
	                    int id = event.getPointerId(i);  
	                    int x = (int) event.getX(i);  
	                    int y = (int) event.getY(i);  
	                    drawCrosshairsAndText(x, y, touchPaints[id], i, id, c);  
	                }  
	                for (int i = 0; i < pointerCount; i++) {  
	                    int id = event.getPointerId(i);  
	                    int x = (int) event.getX(i);  
	                    int y = (int) event.getY(i);  
	                    drawCircle(x, y, touchPaints[id], c);  
	                }  
	            }  
	            // 画完后，unlock  
	            getHolder().unlockCanvasAndPost(c);  
	        }  
	        return true;  
	    }  
	   
	    /**  
	     * 画十字及坐标信息  
	     *  
	     * @param x  
	     * @param y  
	     * @param paint  
	     * @param ptr  
	     * @param id  
	     * @param c  
	     */  
	    private void drawCrosshairsAndText(int x, int y, Paint paint, int ptr,  
	            int id, Canvas c) {  
	        c.drawLine(0, y, width, y, paint);  
	        c.drawLine(x, 0, x, height, paint);  
	        int textY = (int) ((15 + 20 * ptr) * scale);  
	        c.drawText("x" + ptr + "=" + x, 10 * scale, textY, textPaint);  
	        c.drawText("y" + ptr + "=" + y, 70 * scale, textY, textPaint);  
	        c.drawText("id" + ptr + "=" + id, width - 55 * scale, textY, textPaint);  
	    }  
	   
	    /**  
	     * 画圆  
	     *  
	     * @param x  
	     * @param y  
	     * @param paint  
	     * @param c  
	     */  
	    private void drawCircle(int x, int y, Paint paint, Canvas c) {  
	        c.drawCircle(x, y, 40 * scale, paint);  
	    }
	    /*  
	     * 进入程序时背景画成黑色，然后把“START_TEXT”写到屏幕  
	     */  
	    public void surfaceChanged(SurfaceHolder holder, int format, int width,  
	            int height) {  
	        this.width = width;  
	        this.height = height;  
	        if (width > height) {  
	            this.scale = width / 480f;  
	        } else {  
	            this.scale = height / 480f;  
	        }  
	        textPaint.setTextSize(14 * scale);  
	        Canvas c = getHolder().lockCanvas();  
	        if (c != null) {  
	            // 背景黑色  
	            c.drawColor(Color.BLACK);  
	            float tWidth = textPaint.measureText(START_TEXT);  
	            c.drawText(START_TEXT, width / 2 - tWidth / 2, height / 2,  
	                    textPaint);  
	            getHolder().unlockCanvasAndPost(c);  
	        }  
	    }

		@Override
		public void surfaceCreated(SurfaceHolder holder) {
			// TODO Auto-generated method stub
			
		}

		@Override
		public void surfaceDestroyed(SurfaceHolder holder) {
			// TODO Auto-generated method stub
			
		}  
	}
